1. Field of the Invention
The present invention relates to a photographic film processing apparatus for processing medical, industrial and general-purpose photographic film, radiographic films, or printing paper.
2. Description of the Related Art
Generally, in a dental clinic or research laboratory, an exposed photographic film or radiographic film (hereinafter referred to simply as "film") is immersed in a developing solution contained in a processing container for developing, the developed film is transferred from the processing container through the air to another processing container containing a fixing solution for fixing or the film is immersed in a developing-and-fixing solution contained in a processing container for developing and fixing. When a large number of films are processed at a time or the developing process is performed frequently, the processing solution is contained respectively in processing tanks each having a comparatively large capacity and provided with conveying means, such as conveyor rollers, and films are fed successively to the processing containers for continuous developing. The deteriorated developing solution and the fixing solution (hereinafter referred to inclusively as "processing liquids") deteriorated due to repeated use for developing and fixing are disposed of after being diluted and neutralized according to relevant laws and regulations.
Generally, the processing container or the processing tank for containing the processing liquid is opened to the atmosphere to feed a film into and to take out the same from the container or the tank. Accordingly, the characteristics of the processing liquid deteriorate as the same is used repeatedly and deteriorate naturally with time due to oxidation by air that occurs in the surface of the processing liquid. Furthermore, there is the possibility that the processing liquid wetting the surfaces of the components, such as the conveyor rollers, of the processing apparatus dries and solidifies in particles or crystals, and the particles or crystals damage the film.
Accordingly, when processing a film by a conventional photographic film processing method that passes the film through processing containers or processing tanks containing processing liquids, the characteristics of the processing liquids must be controlled continuously to replenish the processing containers with the processing liquids or to change the processing liquids at the appropriate time, and the components of the processing apparatus in contact with the processing liquids must be frequently cleaned to remove the particles or crystals formed by drying the processing liquids.
However, since such control of the processing solutions and maintenance of the processing apparatus are comparatively troublesome, it often happens that unclear images are formed or images are damaged as a consequence of failure in replenishing the processing tanks, changing the processing liquids or cleaning the components of the processing apparatus at the appropriate time. Since the exhausted processing liquids must be disposed of after dilution and neutralization according to relevant laws and regulations, and the disposal of a large quantity of waste processing liquid requires much time and large cost. Therefore, there has been a demand for a compact photographic film processing apparatus capable of stably processing films by using a comparatively small quantity of a processing liquid and of making cleaning work unnecessary or reducing the frequency of cleaning work.
The inventors had continuously made efforts in improving the conventional photographic film processing apparatus and previously proposed an improved photographic film processing tank in Japanese Patents Nos. 1773397 (Laid Open No. 4-62657) and 1773398 (Laid Open No. 4-62658). This previously proposed photographic film processing tank is provided with a film inlet slit and a film outlet slit which are immersed in water to suppress the deterioration of a processing liquid contained in the photographic film processing tank due to oxidation, and to prevent the solidification and crystallization of the ingredients of the processing liquid due to drying so that the film will not be damaged by the particles or crystals of the ingredients of the processing liquid.
The inventors incorporated further improvements into this previously proposed photographic film processing tank and proposed a photographic film processing apparatus as shown in FIGS. 4(a) and 5(a) capable of stably processing films by using a very small quantity of a processing liquid and of doing away with troublesome work for supplying and changing a new processing liquid and for cleaning the components in Japanese Patent Application No. Hei 4-1721 (Laid Open No. 5-188559). FIGS. 4(a) and 5(a) are schematic sectional views of a photographic film processing apparatus in a second embodiment according to the invention applied for in Japanese Patent Application No. Hei 4-1721 and a photographic film processing apparatus in a modification of the former. As shown in FIG. 4(a) (FIG. 5(a)), the photographic film processing apparatus is provided with processing vessels 42 (52) each having a flat processing chamber 43 (53), a film inlet slit 44 (54) and a film outlet slit 44 (54). The processing vessels 42 (52) are immersed in fresh water W contained in a water tank 41 (51), and a processing liquid is supplied into the flat processing chambers 43 (53) so that the processing liquid will flow alternately in laterally opposite directions to uniformly wet a film F traveling through the processing chambers 43 (53). Thus, this photographic film processing apparatus is capable of stably processing films by using only a very small quantity of the processing liquid, does not require troublesome work for supplying and changing the processing liquid and for cleaning the components, and facilitates the disposal of the exhausted processing liquid.
Since the processing vessel 42 (52) provided with the film inlet slit 44 (54) and the film outlet slit 44 (54) is immersed in the water W, the processing chamber 43 (53) is pressurized so as to balance the pressure of the water W to suppress a leakage of the water W into the processing chamber 43 (53). Although a leakage of the water W into the processing chamber 43 (53) can be suppressed to some extent by this means, the water W leaks unavoidably into the processing chamber 43 (53) or the processing liquid leaks unavoidably into the water W through the film inlet slit 44 (54) and the film outlet slit 44 (54). As shown in FIG. 4(b), each of the film inlet slit 44 and the film outlet slit 44 of the photographic film processing apparatus shown in FIG. 4(a) is sealed with a pair of soft, elastic sealing lips 45 to prevent the flow of the water W into the processing chamber 43 and the flow of the processing liquid into the water W. As shown in FIG. 5(b), a pair of rollers 55 and 55' formed of an elastic material is disposed in contact with each other at each of the film inlet slit 54 and the film outlet slit 54 of the photographic film processing apparatus shown in FIG. 5(a), and the gaps between the end wall of the processing chamber 53 and the rollers 55 and 55' are sealed with rubber blades 56. In this photographic film processing apparatus, the rollers 55 and 55' function as means for conveying the film F as well as sealing members.
However, the inventors made further examination of this previously proposed photographic film processing apparatus, and found that there still was room for further improvement in the photographic film processing apparatus.
Although the pairs of flexible sealing lips 45 of the processing vessel shown in FIG. 4(b) are formed of a soft, elastic material, there is the possibility that the sensitized layer of the film is rubbed by the flexible sealing lips 45 and scratches are formed in the sensitized layer when the film passes through the space between the pair of flexible lips 45, which is a significant problem particularly when a minute, sharp image must be formed on the film. When the film passes through the processing vessel shown in FIG. 5(b), the film is not rubbed and the sensitized layer will not be scratched because the film is advanced by the rotating pairs of rollers 55 and 55'. However, additional power is required to rotate the rollers 55 and 55' against the frictional resistance of the rubber blades 56 in close frictional contact with the rollers 55 and 55'. Particularly, when the photographic film processing apparatus is provided with a plurality of processing vessels as shown in FIG. 5(b), the additional power required for rotating the rollers 55 and 55' against the frictional resistance of the rubber blades 56 is considerably large and not ignorable. Furthermore, since the rubber blades 56 are abraded, the processing vessels need frequent maintenance service and inspection.
Although this previously proposed photographic film processing apparatus is capable of stably processing films by using a very small quantity of the processing liquid by making the processing liquid flow alternately in laterally opposite directions in each processing vessel so that the film traveling through the processing vessel is wetted uniformly with the processing liquid, the contact speed of the film, i.e., the speed of the film relative to the processing liquid, is limited because the flow of the processing liquid must inevitably be stopped temporarily when reversing the direction of flow of the processing liquid, which is a restrictive factor on increasing processing speed for quick processing.